ADPG-PPase has been studied in plants and has been purified (to varying degrees) from spinach, maize, potato, rice, wheat, pea and barley (See, e.g., Anderson, J. M. et al. (1990), supra; Kleczkowski, L. A., et al. Plant Physiol. 101: 179-186).
Complete or partial cDNAs for ADPG-PPase subunits have been cloned from wheat, corn, potato, rice, spinach and barley (See, e.g., Bhave, M. R. et al. (1990) The Plant Cell 2: 531-538; Bae, J. M. et al. (1990) Maydics 3:317-322; and Nakata, P. A. et al. (1991) Plant Molecular Biology 17:1089-1093).
In potato tubers, antisense inhibition of ADPG-PPase reduces starch levels compared to wild-type (Muller-Rober, B., et al. (1992) EMBO J. 11: 1229-1238). In corn endosperm culture, antisense inhibition of ADPG-PPase reduces ADPG-PPase activity (W093/09237). Over-expression of an E. Coli ADPG-PPase regulatory mutant in transgenic tobacco calli, tomato leaves, and potato tubers results in increased starch production (Kishore, G. M. (1991) International patent application number PCT/US91/04036; Stark et al., Science, 258:287-292 (1992)).
In pea, ADPG-PPase has been localized to the chloroplast in leaves (Preiss, J. (1991) Oxford Surveys of Plant Molecular & Cell Biology 7: 59-114) and in pea seeds ADPG-PPase activity has been shown to coincide with starch synthesis during seed development (Turner, J. F. (1969) Aust. J. Biol. Sci., 22:1145-1151).
The mutant rb locus confers on pea embryos a reduction in starch and an increase in sugars (Kooistra, E. (1962) Euphytica 11: 357-373), and is also associated with ten-fold reduced levels of ADPG-PPase activity (Smith, A. M., et al. (1989) Plant Physiol. 89: 1279-1284).